Recent electrostatic discharge test apparatuses have a function of reporting occurrence of gaseous discharge. For example, Non-Patent Document 1 includes a description regarding an electrostatic tester having a “discharge detection function” of checking whether or not gaseous discharge has occurred. However, mere use of this discharge detection function does not allow us to know the timing at which discharge occurred and the instantaneous voltage at the time of occurrence of discharge. Therefore, information sufficient to consider a technique for suppressing discharge has not been obtained.
Meanwhile, electrostatic discharge ESD has a short rising time of 1 ns or less and a high voltage of about several hundreds of volts to 30 kV. Since a probe, such as a potential divider, which allows an oscilloscope to measure such a steep high voltage waveform is not available on the market, there is a problem in that electrostatic discharge cannot be measured at present.